Teuman ii



(No Model.)

T. H. ALDRICH.

BLOWPIPE. No. 469,670. Patented Mar. 1. 1892.

mm. f (2g 6 MM J M 07 Ga/151m MA.

UNITED STATES PATENT OFFICE.

TRUMAN II. ALDRICH, OF CINCINNATI, OHIO, ASSIGNOR OF ONE-HALF TO A. G. ROSE, OF SAME PLACE.

BLOW-P! PE.

SPECIFICATION forming part of Letters Patent No. 469,670, dated March 1, 1892.

Application filed April 2, 1891.

To all whom it may concern.-

Be it known that I, TRUMAN H. ALDRICH, a citizen of the United States, residing at Gincinnati, in the county of Hamilton and State of Ohio, have invented a certain new and useful Improvement in Blow-Pipes, of which the following is a specification.

My invention relates to blow-pipes, more especially to blow-pipes for dental uses. It is usual for dentists to remove the cuttings or chips made by the excavator or drill from the cavity and to dry the tooth by means of a blast of heated air. In dental blow-pipes as heretofore constructed the air has been heated by passing it through a chamber heated by exposure to a flame. This mode of heating is objectionable, because the chamber is slow to heat, and when removed from the flame rapidly cools, requiring frequent reheating and consequent delay in the operation. It is further objectionable because the heat is greatest at the surface and the instrument is likely to come in contact with and burn the face of the patient.

It is the object of my invention to avoid these objections; and it consists in the combination and arrangement of parts hereinafter specified.

In the drawings, Figure 1 represents a side elevation, partly in section, of my improved apparatus; and Fig. 2, an enlarged View in section of one of the binding-posts for the conductor.

A is a tube provided at one end with an annular cap B, to which an elastic bulb O, provided with an inlet-valve 0, may be secured. The other end of the tube is preferably spun to a point, forming an injectionnozzle D. In the interior of the tube A, I place a substance adapted to be electrically heated, preferably a coil of wire E, one end of which may be secured to a screw F, taking through the tube and attached thereto by a nut f. The other end of the wire may take between the head g of a screw G and a washer g, taking over the latter, the screw G taking through an aperture 0. in the tube and being held in place by a nut g The screw G is electrically insulated from the tube. This may be accomplished by enlarging the aperture a sufficiently to allow the screw G to take therethrough without con- Serial No. 387,346. (No model.)

tacting with the tube and by providing washers g g of non-conducting material, one of which is adapted to take between the tube and washer g and the other between the tube and nut 9 ires h 7t, connected to a battery or other source of electricity H, are adapted to be joined, respectively, to the screws F and G and form electrical connection with the coil E. The wires may be held in place by nuts f and g taking, respectively, over the screws F and G, thereby forming binding-posts for the same.

I is a switch adapted to break the electric circuit. I prefer to separate the electricallyheated substance from the tube by a layer K of non-heat-conducting material, such as asbestus or other material which will yield somewhat to compensate for expansion. It is desirable that the conductor in the tube be heated and the wires connecting with the source of electricity remain practically unaffected by the electric current. I therefore employ a conductor in the tube of greater electric resistance than the wires connecting with the electric source.

In my improved device the surface over which the air or other matter passes is heated immediately upon the closing of the electric circuit and retains a uniform heat indefinitely. The operator is in no danger of coming in contact with heated surfaces or burning the patient, as is the case with the old devices.

I claim The combination, in a dental blow-pipe, of a tube, an injection-nozzle at the end thereof, a source of electricity, connections between the source of electricity and contacts within the tube, an electric conductor taking from one contact through the tube in the form of a cylindrical coil and returning through itself to the other contact, a non-heat-conducting elastic packing between the coil and the wall of the tube, and an elastic bulb or equivalent means attached to the tube and adapted to force a current of air therethrough, substantially as and for the purpose specified.

TRUMAN H. ALDRICH. Witnesses:

JAMEs N. RAMsEY, AUeUsT F. IIERBSLEB. 

